US20080273936A1 - Method for Producing Rotationally Symmetrical, undercut Contours - Google Patents

Method for Producing Rotationally Symmetrical, undercut Contours Download PDF

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Publication number
US20080273936A1
US20080273936A1 US11/721,699 US72169905A US2008273936A1 US 20080273936 A1 US20080273936 A1 US 20080273936A1 US 72169905 A US72169905 A US 72169905A US 2008273936 A1 US2008273936 A1 US 2008273936A1
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US
United States
Prior art keywords
piston
tool
section
worked
undercut
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/721,699
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English (en)
Inventor
Ralph Bernhardt
Matthias Prussak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CDP Bharat Forge GmbH
Original Assignee
CDP Bharat Forge GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CDP Bharat Forge GmbH filed Critical CDP Bharat Forge GmbH
Assigned to CDP BHARAT FORGE GMBH reassignment CDP BHARAT FORGE GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BERNHARDT, RALPH, PRUSSAK, MATTHIAS
Publication of US20080273936A1 publication Critical patent/US20080273936A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/18—Making machine elements pistons or plungers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/063—Friction heat forging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/18—Making machine elements pistons or plungers
    • B21K1/185—Making machine elements pistons or plungers with cooling channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K21/00—Making hollow articles not covered by a single preceding sub-group
    • B21K21/12—Shaping end portions of hollow articles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T409/00—Gear cutting, milling, or planing
    • Y10T409/30—Milling
    • Y10T409/303752—Process
    • Y10T409/303808—Process including infeeding

Definitions

  • the present invention relates to a method for the chipless, non-cutting production of substantially rotationally symmetrical, undercut contours on a workpiece, as well as to a workpiece manufactured by means of this method.
  • Undercut contours of this kind can be formed in particular on sub-sections of workpieces manufactured by forging, casting or cutting production.
  • rotationally symmetrical, undercut contours such as, for example, cooling ducts on pistons for commercial vehicle diesel engines are manufactured by means of cutting. That is, a starting workpiece manufactured, for example, by forging or casting, is machined by a material-removing method such as, turning, milling or cutting to produce an undercut contour.
  • the drawbacks of the known methods are, on the one hand, the high degree of chipping, particularly in the case of the inside contours of mass-produced goods such as, pistons, which need to be machined in their entirety, and, on the other hand, the associated grain interruption in the conventionally fabricated product. Such an interruption leads to structurally weaker workpieces, and thus adversely affects wear resistance, lifetime and costs of the final product.
  • a workpiece to be processed using said method comprises at least one sub-section to be worked having a substantially symmetrical, preferably rotationally symmetrical, initial contour such as a polygonal, cylindrical or right circular cone-shaped shaft, and an axis of rotation about which the workpiece can be rotated during processing.
  • the sub-section to be worked of the workpiece can be designed to be in either solid, partly solid or hollow form.
  • the workpiece is first clamped into a collet at a first end portion not to be worked for example by positive locking and/or friction locking. The workpiece can then be moved with the collet towards a tool and relative thereto.
  • the tool which rotates with constant or variable speed about a center axis relative to the workpiece, is abutted against a substantially symmetrical, preferably rotationally symmetrical, second end portion to be worked of the workpiece. It is thus possible in the working step to chiplessly produce undercut contours such as cooling ducts on a piston while the tool applies axial pressure to the second end portion.
  • undercut contours can readily be given the machining dimensions such that only a final mechanical fine-machining process is required to obtain the final product. As a result, manufacturing is quicker and thus less expensive.
  • the movement of workpiece and tool towards each other, which is associated with the working step is a feed motion which provides the axial pressure required for working.
  • This feed motion can be carried out by the workpiece and collet, by the tool or by a parallel feed motion.
  • the undercut contour which is to be formed in the working step can be orientated inwardly or outwardly in a rotationally symmetrical manner with respect to the initial contour of the workpiece sub-section to be worked.
  • Inner and/or outer cooling ducts of diesel engine pistons, which have to date been produced by chipping milling, can be cited herein as specific examples of inwardly or outwardly orientated contours.
  • Outwardly orientated undercut contours can, for example, also be found on front axle housings which have to date likewise been produced by chipping machining.
  • the method according to the invention makes it possible to produce both types of contours in a structurally stabler manner.
  • the tool used in the method according to the invention can have a symmetrical or asymmetrical tool contour, depending on the workpiece to be processed. Furthermore, it has proven to be advantageous for the tool to rotate with a first speed and for the workpiece to rotate with a second speed that can be selected to be different from the first speed. The speed of the tool may differ from that of the workpiece by up to 30%. If the drive system of the tool and/or of the collet additionally has a freewheel, the first and/or second speed can be altered. This leads to an extraordinarily regular flow of material with consequently improved properties of the final product.
  • the axis of rotation of the sub-section to be worked and the center axis of the tool may be aligned. If, however, lower friction, i.e. a smaller friction surface, is desired, as in the case of, for example, workpieces in which the sub-section to be worked is solid, the axis of rotation of the sub-section to be worked and the center axis of the tool may deviate, according to a further preferred embodiment, by an amount of eccentricity e.
  • the amount of eccentricity can be adjusted in that the rotating tool rotates in an axially oscillating manner about the center axis of the workpiece section to be worked.
  • This axial oscillation is achieved, for example, by way of a radial feed motion of the tool.
  • the reduction of the friction surface moreover offers the advantage of requiring less force and thus less energy for working since there is only partial contact.
  • the entire workpiece is subjected to the method with a temperature distribution that is determined based on preliminary processes, or is heated in a step preceding the method, for example to a forging temperature appropriate for the material.
  • a temperature distribution that is determined based on preliminary processes, or is heated in a step preceding the method, for example to a forging temperature appropriate for the material.
  • the geometry of the undercut is adjusted in that the sub-section to be worked has a defined temperature distribution as a result of, for example, targeted heating in a preceding step.
  • the geometry thereby comprises in particular the length of the formed undercut as well as its clearance. Due to this method feature, working is, on the one hand, simplified (lower flow stress) and, on the other hand, rendered more precise and reproducible.
  • the method according to the invention furthermore makes it possible to determine the exact shape of the undercut outer contour.
  • the undercut outer contour which is to be produced in the working step, is defined by pressing on one or more loose or driven tools. This pressing on can be effected in a substantially radial direction against the undercut being formed.
  • the application of an additional tool such as, for example, a pivotable tool equally serves to define a gap formed by the undercut contour to be formed.
  • the additional tool can thereby be designed so that it can be used to adjust, in a defined manner and in one operation, not only the outer contour, but also the front surface, the sharp-edged transition from the front surface to the lateral surface, and the clearance. In this way, complicated undercut contours can be accurately custom-formed.
  • a workpiece which is produced using the method according to the invention is accordingly characterized by a continuous and uninterrupted grain flow which is substantially parallel to the formed undercut contour.
  • Such a grain flow increases the loading capacity, lifetime and flawlessness of the material and thus workpiece quality as a whole.
  • it takes considerably less time to produce the finished workpiece, which positively affects the cost-benefit ratio.
  • the workpieces that can be processed by the presented method may consist of a multiplicity of materials.
  • steel is used for high-performance engines of commercial vehicles, whereas aluminum-silicon alloys are used for low compression ratio passenger car engines.
  • FIG. 1 schematically shows the arrangement of the components that are required by the method, wherein a steel piston is selected as the workpiece.
  • FIG. 2 shows a working sequence according to claim 1 on the example of a forged steel piston as the starting workpiece.
  • FIG. 3 shows the optional custom-forming of the outer contour by means of a driven or freely supported tool, as well as of the clearance by means of a pivotable tool.
  • FIG. 4 shows, as a further example, a section taken through a front-axle housing in which the outer contour to be worked is illustrated before and after the working process.
  • FIG. 5 shows a working sequence for forming a gas-tight cooling duct, wherein the flow of material is directed inwardly.
  • FIGS. 6 and 7 show further working sequences for forming a gas-tight cooling duct but with an outwardly directed flow of material.
  • a rotationally symmetrical, undercut outer contour is formed on a forged steel piston as is used in high-performance diesel engines.
  • the method according to the invention is carried out by means of a device illustrated in FIG. 1 , which comprises a collet 11 for clamping in a workpiece 13 , a tool 12 for working the workpiece, as well as a means (not shown) for feeding the collet with the workpiece 13 to the tool 12 .
  • the tool 12 comprises a circumferential rim which serves to radially confine the flow of material produced during working.
  • the steel piston which is used in the example embodiment as workpiece 13 comprises a hollow rotationally symmetrical sub-section 14 which constitutes the end to be worked of the steel piston.
  • the working tool 12 is abutted against this sub-section, with the axial pressure required for working being applied by means of the feed motion.
  • the collet 11 can be rotated, together with the clamped-in workpiece 13 , about an axis of rotation 15 , whilst the tool 12 is rotatable about its center axis 16 .
  • Both the collet and the tool comprise a rotary drive (not shown) which may respectively have a freewheel and whose speed can each be separately adjusted by means of a speed control.
  • the center axis 16 of the tool can, on the one hand, coincide with the axis of rotation 15 of the collet or can be offset therefrom in parallel (amount of eccentricity e>0).
  • the friction occurring between the tool 12 and the workpiece sub-section 14 to be worked is produced solely by a difference between the peripheral speeds of tool 12 and collet 11 and is thus determined by the speed control. It is thus possible, particularly with very soft workpiece materials like aluminium, to limit this friction to a minimum in order to avoid possible loss of material that might result from excessive friction. If, however, harder materials like steel are used, reduced friction between the tool 12 and the workpiece sub-section 14 to be worked is often desirable in order to achieve a limitation of the resulting forces and moments. It is possible for this purpose to adjust the offset between the axes of rotation of workpiece and tool, i.e. the amount of eccentricity.
  • FIG. 2 shows an example of a working sequence in which a cooling duct 22 is formed as an undercut outer contour on a forged steel piston 21 .
  • the piston is fed to the tool under axial pressure.
  • the freewheel of the rotary tool drive is utilized such that the speed of the tool, n u adapts itself automatically to the rotational speed of the shaped part which is formed on the contact surface of tool and workpiece. Due to the resulting uniform flow of material, a flange-like expansion 23 of the piston sub-section to be worked is first produced. With further axial feed pressure, progressive flow of material leads to a bending over/flanging of the contour and can then be confined radially by the raised edge 17 of the tool 12 so as to form the undercut outer piston contour to be achieved.
  • FIG. 3 shows two further working measures which serve to better define the undercut contour to be formed.
  • an additional tool 31 which has a cylindrical design here, is fed under radial pressure to the lateral surface of the newly formed outer contour by a feeding mechanism 32 and thus confines the radially outwardly directed flow of material produced during working.
  • the outer diameter 33 of the newly formed outer contour is brought to the requisite value.
  • the additional tool may either be freely supported or driven with a speed n 3 of, for example, 750 min ⁇ 1 .
  • the clearance 34 of the cooling duct can furthermore be custom-formed using a pivotable tool 35 .
  • This tool is designed to be L-shaped, with the long arm 36 abutting against the surface axially opposite to the feeding direction of the bent-over, undercut contour.
  • the short arm 37 engages the gap from the outside and lies on the radially inwardly facing surface of the bent-over, undercut contour.
  • the pivotable tool 35 confines, if necessary, the flow of material both radially inwardly and axially against the feeding direction of the piston collet.
  • FIG. 4 shows a section through a front-axle housing 38 on which the sub-section to be worked is illustrated before 39 and after 40 the working step.
  • the outer contour which was cylindrical prior to working, was shaped into the desired, outwardly orientated outer contour with undercut section 41 .
  • FIG. 5 illustrates an example of a working sequence of a steel piston in which the flow of material is inwardly orientated.
  • the rotationally symmetrical sub-section 50 to be worked of the piston is bent over inwardly, step by step, by the method until it comes into contact with the edge 51 of the combustion bowl 52 and thus forms a closed, gas-tight cooling duct 53 .
  • a gas-tight cooling duct can also be formed on a piston using an outwardly directed flow of material for working, as is shown in the working sequence of FIG. 6 .
  • a separate ring support 62 is fitted in the outer contour of the piston that terminates the cooling duct radially outwardly. Due to the method according to the invention, the sub-section 60 of the piston, which is at first cylindrical, is reshaped into a flange-like expansion 61 . This ultimately comes to rest, in an axial direction, with its side facing the piston on the ring support 62 , by means of which expansion 61 and ring support 62 form the gas-tight cooling duct 63 .

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
US11/721,699 2004-12-16 2005-12-05 Method for Producing Rotationally Symmetrical, undercut Contours Abandoned US20080273936A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/EP2004/014369 WO2006063608A1 (de) 2004-12-16 2004-12-16 Verfahren zur herstellung rotationssymmetrischer, hinterschnittener konturen
PCT/EP2005/012995 WO2006063710A1 (de) 2004-12-16 2005-12-05 Verfahren zur herstellung rotationssymmetrischer, hinterschnittener konturen

Publications (1)

Publication Number Publication Date
US20080273936A1 true US20080273936A1 (en) 2008-11-06

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ID=34960033

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Application Number Title Priority Date Filing Date
US11/721,699 Abandoned US20080273936A1 (en) 2004-12-16 2005-12-05 Method for Producing Rotationally Symmetrical, undercut Contours

Country Status (9)

Country Link
US (1) US20080273936A1 (ja)
EP (1) EP1833627A1 (ja)
JP (1) JP2008524482A (ja)
KR (1) KR20070086113A (ja)
CN (1) CN100475383C (ja)
BR (1) BRPI0519660A2 (ja)
CA (1) CA2588931A1 (ja)
MX (1) MX2007006953A (ja)
WO (2) WO2006063608A1 (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013086297A1 (en) 2011-12-08 2013-06-13 Federal-Mogul Corporation One-piece piston with improved combustion bowl rim region and method of manufacture

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102319920B (zh) * 2011-06-10 2013-06-19 江西昌河航空工业有限公司 非完整圆柱面或非规则圆柱回转曲面的偏心铣削加工方法

Family Cites Families (12)

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Publication number Priority date Publication date Assignee Title
CH230566A (de) * 1942-03-24 1944-01-15 Mahle Kg Verfahren zur Herstellung von geschmiedeten Kolben für Brennkraftmaschinen.
DE1103698B (de) * 1959-10-23 1961-03-30 Schmidt Gmbh Karl Durch Schmieden oder Pressen hergestellter Kolben, vorzugsweise aus einer Aluminium-legierung fuer Brennkraftmaschinen und Kompressoren
WO1982000013A1 (en) * 1980-06-26 1982-01-07 Pirogov V Method of obtaining butt-end wall with concentric recess in a tubular workpiece
DE3502248C1 (de) * 1985-01-24 1986-05-07 Berchem & Schaberg Gmbh, 4650 Gelsenkirchen Verfahren zur Herstellung eines einteiligen Kolbens fuer einen Verbrennungsmotor durch Schmieden
DE3713191C1 (en) * 1986-12-24 1988-07-14 Mahle Gmbh Method for the manufacture of a forged head of a two-part piston for internal combustion engines
JP2819085B2 (ja) * 1994-04-01 1998-10-30 株式会社レイズエンジニアリング 回転鍛造装置及びこれを用いた自動車用ホイールの製造方法
DE4431517C2 (de) * 1994-08-11 1997-11-13 Manfred Klever Verfahren zum Formen von Endstücken an rohrförmigen Werkstücken aus Metall
DE19607010C1 (de) * 1996-02-24 1996-12-12 Gfu Ges Fuer Umformung Und Mas Vorrichtung zum Formen eines Endstückes an einem rohrförmigen Werkstück aus Metall und damit hergestellter Druckbehälter
DE19953525C2 (de) * 1999-11-05 2002-04-18 Gfu Ges Fuer Umformung Und Mas Verfahren zur Herstellung eines metallischen Rohrformstückes
CN1223416C (zh) * 2002-06-03 2005-10-19 蒋国语 柴油机输油泵用活塞冷冲压加工方法
JP4253644B2 (ja) * 2004-06-28 2009-04-15 理研鍛造株式会社 内燃機関用ピストンの製造方法
US7104183B2 (en) * 2004-07-07 2006-09-12 Karl Schmidt Unisia, Inc. One-piece steel piston

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013086297A1 (en) 2011-12-08 2013-06-13 Federal-Mogul Corporation One-piece piston with improved combustion bowl rim region and method of manufacture
US9068531B2 (en) 2011-12-08 2015-06-30 Federal-Mogul Corporation One-piece piston with improved combustion bowl rim region and method of manufacture

Also Published As

Publication number Publication date
CA2588931A1 (en) 2006-06-22
BRPI0519660A2 (pt) 2009-03-03
WO2006063710A1 (de) 2006-06-22
CN100475383C (zh) 2009-04-08
CN101072650A (zh) 2007-11-14
JP2008524482A (ja) 2008-07-10
WO2006063608A1 (de) 2006-06-22
EP1833627A1 (de) 2007-09-19
MX2007006953A (es) 2007-08-06
KR20070086113A (ko) 2007-08-27

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Owner name: CDP BHARAT FORGE GMBH, GERMAN DEMOCRATIC REPUBLIC

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BERNHARDT, RALPH;PRUSSAK, MATTHIAS;REEL/FRAME:020108/0823;SIGNING DATES FROM 20070705 TO 20070725

STCB Information on status: application discontinuation

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